1. Field of the Invention
The present invention relates to an optical disk, and more particularly to an optical disk comprising a recording area and an identification phase-encoded part (PEP) area with pits from which system data on said optical disk is reproduced without tracking.
2. Discussion of the Background
At the present time, various studies are being conducted into the standardization of optical disks. Two types of optical disk systems have been proposed for this standardization. These are the Continuous Composite (CCS) and Discrete Block Format (DBF) systems.
The tracking method differs for these two systems. The CCS system uses the push-pull method, while the sample servo method has been adopted for DBF.
When the tracking methods differ, the drive must identify the type of optical disk from which data is to be reproduced and conform to that optical disk.
Therefore, with this standardization plan, an area called PEP (Phase-Encoded Part) is provided on the optical disk as an identification means so that system data can be reproduced from the disk without tracking.
On an optical disk used in this conventional system, the track pitch for the PEP area and the track pitch for the recording area are the same.
Accordingly, in reproducing data from the PEP area on this conventional optical disk without tracking, the reproduction of the data is readily influenced by the eccentricity of the optical disk. The problem therefore arises that large fluctuations in the signal from the PEP area (PEP signal) occur as a result of this eccentricity.
For this reason, track-on and track-off states occur during beam scanning as a result of the eccentricity of the optical disk. Therefore, the amplitude of the PEP signal (PEP amplitude) undergoes large changes.
Data read-out errors occur in an optical disk using a conventional system when data from the PEP area is reproduced because of the large variations in the PEP amplitude. There is also a strong possibility that the device will be unable to identify the type of optical disk. The system data therefore becomes unreliable, causing inconvenience because of the resulting low confidence.